1. Field of the Invention
The present invention relates to the earth boring arts. In particular, the invention relates to a well annulus packer having a plurality of independent conduits passing through the packer whereby the packer seal integrity is maintained with the casing wall or well bore.
2. Description of the Prior Art
"Packer" is the term given to an apparatus for axially separating adjacent sections of a borehole or casing annulus with a fluid-tight barrier. Usually, the packer is combined with one or more additional tools such as a slip that is set to hold the packer in place.
The set of a packer is often merely one step in a well working procedure that is either preceded or followed by other procedures and manipulations either above or below the packer. Commonly, pressure and/or temperature measurements from either above or below the packer are transmitted to the surface. Usually, such data is carried on electrical or fiber optic data transmission cable. In other cases, power transmission fluid is delivered to and returned from a downhole fluid motor.
Operational circumstances as described above require one or more sealed conduits across the packer barrier. In the past, such by-pass conduits have been routed through an annulus between a concentric pair of cylindrical mandrels. The inner mandrel serves as the inner conduit for primary well production flow, for example. The outer mandrel serves as the internal base surface for an expandable packer element. An annular space between the inner and outer mandrels routes the fluid or data carrier conduits. That portion of the annular space between the conduits is filled with some form of filler material to maintain a seal between the upper and lower bore zones.
As the need arises for larger fluid and data transmission cable, an increased inter-mandrel annulus is essential to accommodate the increased cable size. However, an increased inter-mandrel annulus requires a larger expandable element mandrel. If the prior art pattern is followed, it is ultimately necessary to increase the borehole size to accommodate larger data cable or fluid circulation conduits: an exponentially expensive consequence.
It is, therefore, an objective of the present invention to provide larger packer feed-through conduits than is possible by prior art techniques without increasing the borehole or casing size.
Another object of the invention is a packer feed-through technique that eliminates the necessity for a second mandrel in the assembly.
A still further object of the invention is to more efficiently use the annulus area between a packer mandrel and the expandable element.